1. Field of the Invention
The present invention relates generally to hand held electrical tools and particularly to a multi-purpose plier for the purpose of forming, stripping, crimping and cutting electrical wire.
2. Description of the Background Art
FIG. 1 shows a prior art conventional hand held multi-tool typically used to perform the steps outlined in the following text.
The guidelines for joining electrical wire to a screw terminal for the purpose of creating a mechanical pressure connection vary. Wiring 1-2-3 (The Home Depot, 2005, Second Edition) home improvement book outlines a four step process for joining wire to a terminal using long-nose pliers (also known as chain-nose or needle-nose pliers). To create a loop at the end of the conductor the book suggests using long-nose pliers or the tip 25 of a pair of wire strippers (multi-tool) both of which have asymmetrical serrated jaws with sharp squared off edges. However, step 2 demonstrates two options; option A shows how to “bend a question mark” using long-nose pliers and option B shows how to “use a wire-bending screwdriver” to form a U-shaped loop. The book does not adopt a standard since these two methods create different loop geometries. The long-nose plier is pictured forming the conventional question mark while the wire-bending screwdriver creates a hook.
You can Build: Wiring (Sunset, 2009) home improvement book demonstrates a four step process for looping the end of a conductor. Just like in The Home Depot book, Sunset suggests to create a loop at the end of the conductor using long-nose pliers or the tip 25 of a pair of wire strippers (multi-tool) both of which have asymmetrical serrated jaws with sharp squared off edges. The same two options are provided—using the tip of a pair of wire strippers (multi-tool) or the “looping screwdriver” method. Again, the book does not adopt a standard since both methods of bending wire create different loop geometries. The multi-tool is pictured forming the conventional question mark. However, the pictures show the tool damaging the bare wire by creating nicks and scratches during the four step wire forming process. The two pictures that demonstrate attaching wire to a screw-down terminal show a bare conductor severely mutilated from the sharp serrated alligator jaws of the long-nose plier. The book states that “[s]urface nicks, like the ones visible in the four steps on the opposite page, are not a concern.” However, section 110.14 (A) of the 2008 National Electric Code (NEC) states that connection of conductors to terminal parts shall ensure a thoroughly good connection without damaging the conductors and shall be made by means of pressure connectors (including set-screw type), solder lugs, or splices to flexible leads. Also, terminal connections come under lots of stress when wired devices such as switches and receptacles are pushed into electrical boxes and any nicks will weaken the wire and may cause it to break no matter how superficial the marks may seem.
Complete Wiring (Stanley, 2008, Second Edition) home improvement book demonstrates a five step process for joining wire to a terminal. Just like in The Home Depot and Sunset books, Stanley suggests to create a loop at the end of the conductor using long-nose pliers or the tip 25 of a pair of wire strippers (multi-tool) both of which have asymmetrical serrated jaws with sharp squared off edges. The same two options are provided—using the tip of a pair of long-nose pliers or the “wire-bending screwdriver” method. The book states that the “handy” wire-bending screwdriver can form “a perfect loop every time” in wire ends. Again, the book does not adopt a standard since both methods of bending wire create different loop geometries. Both the long-nose and multi-tool pliers are pictured forming the conventional question mark.
The Complete Guide to Wiring (Black & Decker, 2008, Fourth Edition) home improvement book demonstrates a three step process for connecting wires to screw terminals. Step 2 shows a pair of “needle-nose” pliers forming a “C-shaped loop” and that “[t]he wire should have no scratches or nicks.” Avoiding damage to the conductor is nearly impossible with long-nose pliers due to the sharp raised edges on the alligator jaw surfaces. The C-shaped loop pictured in the book is the same type of loop that the wire bending screwdriver is capable of forming.
All the books show either a long-nose plier or a multi-tool with a plier-nose 25, that acts much like a long-nose plier, grabbing the wire many times to form the bend in the wire. The more often the sharp plier-nose 25 is repositioned along the wire the more likely the wire is to become marked up and weakened. Section 110.14 (B) commentary text of the 2008 National Electric Code (NEC) presents the following “Installation Method” for correctly terminating wire at wire-binding screw terminals of receptacles and snap switches:                1. The freshly stripped end of the wire is wrapped two-thirds to three-quarters of the distance around the wire-binding screw post, . . . . The loop is made so that rotation of the screw during tightening will tend to wrap the wire around the post rather than unwrap it.        2. The screw is tightened until the wire is snugly in contact with the underside of the screw head and with the contact plate on the wiring device, . . . .        3. The screw is tightened an additional half-turn, thereby providing a firm connection, . . . .        4. The wires should be positioned behind the wiring device to decrease the likelihood of the terminal screws loosening when the device is positioned into the outlet box.        
Three out of the four home improvement books suggest (after hooking a wire around a screw terminal) grabbing the wire on either side of the terminal screw with long-nose pliers and squeezing it around the screw post before tightening the terminal screw. Not only is this step unnecessary according to the preceding NEC commentary but this extra step will also create further damage to the wire when using the sharp serrated edges of a chain-nose plier or the tip 25 of a multi-tool to close the conductor loop. Also, since the thread crests of a terminal screw tend to be sharp, the thread crests could imprint the soft copper or aluminum conductor if the bare wire is pressed too firmly against the thread crests. Furthermore, as the screw is tightened the bare conductor tends to rotate and wrap itself around the terminal screw post to create the three-quarters distance that the preceding NEC commentary describes.
The wire bending screwdriver is an acceptable method for creating a “C-shaped loop” because according to the preceding NEC commentary the wire bending screwdriver creates a two-thirds wrap around the wire binding screw post before the screw is tightened. However, the wire bending screwdriver can be cumbersome to use because the bending spindle is inconveniently located in the middle of the tool where the shank of the screwdriver meets the base of the handle; thus the shank of the wire bending screwdriver tends to get in the way during an electrical installation. Also, the wire bending screwdriver as well as the long-nose (needle-nose or chain-nose) plier require the inconvenience of changing tools since the steps for terminating wire usually require stripping, cutting and forming the wire—not to mention the expense of having to purchase separate tools.
Forming wire loops is a nuisance using conventional long-nose pliers or the plier-nose 25 of a multi-tool. The tedious steps previously outlined in the home improvement books result in inconsistent loops no matter how much care and skill are used to form the controlled bend in the wire. Long-nose pliers have asymmetrical serrated jaws with sharp square surfaces that taper from the pivot to the tip. Most wire strippers and similar multi-tools maintain a convenient plier-nose 25 that are also asymmetrically shaped with sharp serrated jaws. Wire looping holes 27 punched through the jaws of multi-tools have sharp die cut edges that can cut into the wire when forming solid wire. These tools and or tool features are not ideal for bending wire because it is nearly impossible to form wire with a long-nose plier or a multi tool with a plier-nose 25 without cutting into the metal wire. Also, because plier nose 25 is irregularly shaped, repeating the same size wire loop can be difficult and unpredictable with a suffering consequence of creating a loop that may be too large or too small for the screw down terminal post.
Copper and aluminum wire are relatively soft metals according to the Mob's hardness scale and any nicks or scratches in the wire will severely weaken the conductor and may cause the wire to break. The minimal pressure required to form the wire is enough to mark the wire when using a metal surface that is not only sharp and square but also much harder than copper and aluminum. Joining wire to a terminal is an important skill and a key step in most electrical projects. Appropriately formed wire and properly joining wire to a terminal screw ensures the device works properly and doesn't develop a short. Section 110.14 (B) commentary text of the National Electric Code (NEC) states that field observations and trade magazine articles indicate that electrical connection failures have been determined to be the cause of many equipment burnouts and fires. Many of these failures are attributable to improper terminations, poor workmanship, the differing characteristics of dissimilar metals, and improper binding screws or splicing devices. Therefore, prevention is of the utmost importance when it comes to marking up the conductor. Not only is it dangerous but incorrectly forming wire and incorrectly terminating wire at wire-binding screw terminals of receptacles and snap switches wastes time and money by having to start the job over again.
Electrical pliers are very diverse. Some serve a single purpose while others serve multiple purposes. For example, a long-nose plier may only have the capability to cut and bend the electrical wire while another tool may cut, crimp and strip wire insulation from the conductor. Many combinations exist but all, if any, that feature sharp serrated jaws 25 or built-in wire looping holes 27, result in imperfect methods for forming wire and propose a high risk of damaging the wire. Electrical conductors of aluminum, copper-clad or copper are typically cylindrically shaped. Round wire should be formed with round symmetrical shapes with smooth surfaces not asymmetrical shapes with sharp square surfaces such as the typical long-nose plier or multi-tools that feature a plier nose 25.
Thus, what is needed in the art is an electrical multi-tool combined with a reliable forming feature that will accomplish the following:                1) quickly and easily perform controlled loops in metal wire of varying thicknesses/gauges by using round and smooth metal forms, each symmetrically shaped, to create consistent wire loops repeatedly;        2) quickly and easily perform controlled loops in metal wire of varying thicknesses/gauges by using round and smooth metal forms that are proportionally sized to specific terminal screw/stud sizes;        3) will not damage the metal wire or induce surface imperfections during the wire forming process by minimizing surface to surface contact between the round conductor and the round metal forms;        4) will not require the need to change tools since the forming feature is combined with a multi-tool;        5) maintain the slim and narrow profile of the tool for reaching into tight and/or crowded electrical enclosures and cavities as well as working with wire in confined spaces;        6) metal forming tips may also be used for holding, grabbing, gripping, twisting and pulling the wire.It is therefore, to the effective resolution of the aforementioned problems and shortcomings that the present invention is directed.        